The contribution of indirect topographic surveys (photogrammetry and laser scanner) and GPR investigations in the study of the vulnerability of the Abbey of Santa Maria a Mare, Tremiti Islands (Italy)

A proper representation of the conservation status of an Architectural Heritage constitutes a key element of knowledge in order to guarantee the success of a restoration project, the valorization and the fruition of the monument itself. In this context, an important role is played by non-invasive diagnostics and 3D metric surveys that allow acquiring data on potential structural anomalies as well as the location and extent of hidden structures inside the walls. In this paper, the results of the surveys carried out at the Abbey of Santa Maria a Mare, San Nicola, Tremiti Islands (FG, Italy) are presented. The monument is in a significant state of degradation that is testified by the damage of internal and external plaster, water infiltration, presence of molds and superficial lesions on walls and fractures on columns. In order to define restoration interventions, the structure has been analyzed in detail through the realization of 3D metric surveys (photogrammetry and laser scanner) and non-invasive geophysical surveys (Ground Penetrating Radar Technique). The use of non-destructive testing techniques at different scales has provided assessment tools for building characteristics, state of conservation and building safety.